Somewhere in a person's 40s, night driving often starts feeling different — oncoming headlights bloom more, road signs blur a little at dusk, and low-light adaptation takes longer than it used to. This is one of the most common, and most quietly tolerated, age-related eye changes.
Several normal aging processes contribute: the pupil naturally becomes smaller and less responsive with age, letting in less light; the lens gradually yellows and becomes slightly less clear, scattering more light (which is what causes halo and glare effects around bright lights); and the retina's rod cells, responsible for low-light vision, become somewhat less sensitive over time. None of this is a disease process on its own — it's a gradual, expected change.
Vitamin A and zinc both play documented roles in the biochemistry of low-light vision, particularly in how the retina recycles the light-sensitive pigment rhodopsin. Bilberry extract has research specifically on ciliary muscle function relevant to focusing in dim conditions — see our bilberry guide for the specific trial data.